Strange sound on GPi Case & Gameboy emulation

[DieKatz]

Hi there,

i got a strange sound issue when running Gameboy games on my new GPi Case with a Raspberry Pi Zero W and RetroPie 4.5.1.
Not all games, but some of them sound a bit strange. For example the title screen of Tetris sounds like a crank vinyl record.
Inside the game everything seems normal.

Here is an example video

Is there a known issue whitin RetroPie 4.5.1?
I testet:

• all available emulators: Same promlem!
• RetroPie 4.4.0: Also same problem!

But the same ROM file works propper with RecalBox on the same hardware - even on my Pi 3 with RetroPie!
So I think it's not a hardware problem with my GPi Case.

Any idea, what the RecalBox guys do different?

[quicksilver]

@DieKatz Are you saying you tested recalbox on your GPi? If not, then its not exactly an apples to apples comparison. I listened to your video and it didnt sound strange to me. In emulation station try turning the default volume to 100 first, then load the game and adjust the volume wheel to the appropriate level. Perhaps the GPi is adding some type of distortion.

[mitu]

@DieKatz said in Strange sound on GPi Case & Gameboy emulation:

Is there a known issue whitin RetroPie 4.5.1?

Not that we know of. Do you have a comparison startup sound with Recalbox ?

[DieKatz]

Here again for comparison:

• On the Original Gameboy it sounds like this. (the screen is blue, cause i added a backlight module)
• On GPi Case with RecalBox it sounds absolutely correct.
• On GPi Case with RetroPie ...well, i don't realy like it. :-(

Can you hear the difference?

I tried to increase volume to 100% in ES, but that chanched nothing.

No, I still have not found any significant differences in the configuration between RecalBox and RetroPie yet.
That's why I'm asking here, if some one knows about - or even has this problem.

[quicksilver]

@DieKatz Im having a hard time hearing the difference but my earbuds may not be that good :) Which emulator are you using? Any other games that you notice dont sound right?

[DieKatz]

Ah! I think I found something! 💡
When I plug in my headphones, Tetris on my GPi with RetroPie sounds the way it should.

What you finally hear from the speaker is only the sound of the right earphone.
The sound of the left stereo channel is missing! 🤨

Do you know where to set the sound card from stereo to mono, or vice versa?

[quicksilver]

@DieKatz this link maybe useful (I have a GPi as well so I may need to check it out as well). That site has very useful guides for the GPi

https://sinisterspatula.github.io/RetroflagGpiGuides/StereoDownsampleFix

[DieKatz]

Yes! That's it. :-)
Now it sounds perfect.

thx!

[quicksilver]

@DieKatz I just wanted to say thanks for noticing this problem. While playing Sonic 3 on my gpi I noticed that some of the sound effects weren't playing at all. I could never figure out what the problem was. It was the same stereo/mono issue as you were having. So thanks again!